1. Field of the Invention
The present invention relates to a method and an apparatus for growing single-crystalline semiconductor film based on vapor phase growth.
2. Description of the Related Art
FIG. 4 shows one typical example known as a conventional apparatus for depositing a single-crystalline silicon film on a single-crystalline silicon substrate based on vapor phase growth. In a transparent quartz glass-made reaction chamber 21 of this apparatus, a single-crystalline silicon substrate (abbreviated on occasion as "substrate", hereinafter) is set on a susceptor 22 in parallel with a chamber wall 1. The substrate is heated by a series of infrared lamps 23 equipped as a heating unit externally along the chamber wall 1, and reaction gas 10 consisting of carrier gas and source gas is supplied from a reaction gas supply port 24 to be flown over the major plane of the substrate 2. When the substrate 2 is heated to a temperature suitable for the growth of single-crystalline semiconductor film, as high as 800 to 1200.degree. C. for example, a single-crystalline semiconductor film can deposit on the major plane of the substrate 2 by chemical reaction of the reaction gas 10.
The vapor phase growth while the substrate 2 being held in an immobile state will result in a thicker single-crystalline semiconductor film on the upstream side along the flow direction of the reaction gas 10 and in a thinner film on the downstream side. Thus the susceptor 22 for holding the substrate 2 is directly coupled with a rotary shaft 4 to be rotated by a rotary drive unit 7, to assure an uniform thickness of the single-crystalline semiconductor film. To prevent the reaction source from admitting into a back space 11a of the substrate 2 in the reaction chamber 21, a purge gas 3a same as the carrier gas is supplied from a purge gas feed pipe 3, and flown through a purge gas feed section 14 located at the rotary drive unit 7 to completely replacing the space 11a with an atmosphere of the purge gas 3a. The purge gas 3a is thus allowed to flow as indicated by arrow 5 via a gap 6 between the periphery of the susceptor 22 and the chamber wall 1 to reach the major plane side of the substrate 2, and is then brought into confluence with the reaction gas 10 to be discharged from a reaction gas exhaust port 25.
The above apparatus has, however, been suffering from particles generated at the rotary drive unit 7 due to mechanical friction and adhere on the major plane of the substrate 2 after transported thereto together with the purge gas 3a, which could cause defects including stacking fault and abnormally grown matter in a form of protrusion on the surface of the grown film.